Date:   Mon, 15 Aug 2022 14:01:40 +0300
From:   Abel Vesa <abel.vesa@...aro.org>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Magnus Damm <magnus.damm@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Len Brown <lenb@...nel.org>,
        Alexander Stein <alexander.stein@...tq-group.com>,
        Tony Lindgren <tony@...mide.com>,
        Sudeep Holla <sudeep.holla@....com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        John Stultz <jstultz@...gle.com>,
        Doug Anderson <dianders@...omium.org>,
        Guenter Roeck <linux@...ck-us.net>, kernel-team@...roid.com,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        devicetree@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-acpi@...r.kernel.org
Subject: Re: [PATCH v1 0/9] fw_devlink improvements

On 22-08-09 23:00:29, Saravana Kannan wrote:
> This patch series improves fw_devlink in the following ways:
> 
> 1. It no longer cares about a fwnode having a "compatible" property. It
>    figures this our more dynamically. The only expectation is that
>    fwnode that are converted to devices actually get probed by a driver
>    for the dependencies to be enforced correctly.
> 
> 2. Finer grained dependency tracking. fw_devlink will now create device
>    links from the consumer to the actual resource's device (if it has one,
>    Eg: gpio_device) instead of the parent supplier device. This improves
>    things like async suspend/resume ordering, potentially remove the need
>    for frameworks to create device links, more parallelized async probing,
>    and better sync_state() tracking.
> 
> 3. Handle hardware/software quirks where a child firmware node gets
>    populated as a device before its parent firmware node AND actually
>    supplies a non-optional resource to the parent firmware node's
>    device.
> 
> 4. Way more robust at cycle handling (see patch for the insane cases).
> 
> 5. Stops depending on OF_POPULATED to figure out some corner cases.
> 
> 6. Simplifies the work that needs to be done by the firmware specific
>    code.
> 
> This took way too long to get done due to typo bugs I had in my rewrite or
> corner cases I had to find and handle. But it's fairly well tested at this
> point and I expect this to work properly.
> 
> Abel & Doug,
> 
> This should fix your cyclic dependency issues with your display. Can you
> give it a shot please?

Tested the specific case we discussed about here:
https://lore.kernel.org/all/CAGETcx8F0wP+RA0KpjOJeZfc=DVG-MbM_=SkRHD4UhD2ReL7Kw@mail.gmail.com/raw

Thanks for fixing this.

Tested-by: Abel Vesa <abel.vesa@...aro.org>

> 
> Alexander,
> 
> This should fix your issue where the power domain device not having a
> compatible property. Can you give it a shot please?
> 
> Tony,
> 
> This should handle the odd case of the child being the supplier of the
> parent. Can you please give this a shot? I want to make sure the cycle
> detection code handles this properly and treats it like it's NOT a cycle.
> 
> Geert,
> 
> Can you test the renesas stuff I changed please? They should continue
> working like before. Any other sanity test on other hardware would be
> great too.
> 
> Sudeep,
> 
> I don't think there are any unfixed issues you had reported in my other
> patches that this series might fix, but it'll be nice if you could give
> this a sanity test.
> 
> Guenter,
> 
> I don't think this will fix the issue you reported in the amba patch, but
> it's worth a shot because it improves a bunch of corner case handling. So
> it might be better at handling whatever corner cases you might have in the
> qemu platforms.
> 
> Thanks,
> Saravana
> 
> Cc: Abel Vesa <abel.vesa@...aro.org>
> Cc: Alexander Stein <alexander.stein@...tq-group.com>
> Cc: Tony Lindgren <tony@...mide.com>
> Cc: Sudeep Holla <sudeep.holla@....com>
> Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
> Cc: John Stultz <jstultz@...gle.com>
> Cc: Doug Anderson <dianders@...omium.org>
> Cc: Guenter Roeck <linux@...ck-us.net>
> 
> Saravana Kannan (9):
>   driver core: fw_devlink: Don't purge child fwnode's consumer links
>   driver core: fw_devlink: Improve check for fwnode with no
>     device/driver
>   soc: renesas: Move away from using OF_POPULATED for fw_devlink
>   gpiolib: Clear the gpio_device's fwnode initialized flag before adding
>   driver core: fw_devlink: Add DL_FLAG_CYCLE support to device links
>   driver core: fw_devlink: Allow marking a fwnode link as being part of
>     a cycle
>   driver core: fw_devlink: Consolidate device link flag computation
>   driver core: fw_devlink: Make cycle detection more robust
>   of: property: Simplify of_link_to_phandle()
> 
>  drivers/base/core.c             | 437 +++++++++++++++++++++-----------
>  drivers/gpio/gpiolib.c          |   6 +
>  drivers/of/property.c           |  84 +-----
>  drivers/soc/renesas/rcar-sysc.c |   2 +-
>  include/linux/device.h          |   1 +
>  include/linux/fwnode.h          |  12 +-
>  6 files changed, 323 insertions(+), 219 deletions(-)
> 
> -- 
> 2.37.1.559.g78731f0fdb-goog
> 

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